Electro-optical device and electronic apparatus

• US 20050052367A1
• Filed: 08/11/2004
• Published: 03/10/2005
• Est. Priority Date: 08/21/2003
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Miyazawa, Takashi
• Granted Patent: US 7,417,607 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

A capacitor is disposed between a gate of driving transistor of which conduction state correspond to a driving current supplied to a driven element. The gate voltage of the gate of the driving transistor is set by supplying a data current to the driving transistor or a compensating transistor for the driving transistor.

Claims

1. An electro-optical device comprising:

a plurality of scanning lines;

a plurality of data lines;

a plurality of voltage supply lines;

a switch circuit that controls the supply of a voltage to each of the plurality of voltage supply lines; and

a plurality of pixel circuits which are disposed at intersections of the plurality of scanning lines and the plurality of data lines, the plurality of pixels circuits being coupled one of the plurality of voltage supply lines, each of the plurality of pixel circuits including an electro-optical element whose luminance corresponding to a driving current that flows through the electro-optical element, an n-channel driving transistor that is disposed between one of the plurality of voltage supply lines and the electro-optical element and whose a conduction state of the n-channel driving transistor being set according to data, and a capacitor having one electrode coupled with a gate of the n-channel driving transistor and the other electrode coupled with a node that couples the driving transistor and the electro-optical element,

the capacitor retaining electric charge based on a data current supplied in a writing period before the driving period via one of the plurality of data lines.

2. The electro-optical device according to claim 1, each of the plurality of pixel circuits further comprising:

a first switching transistor having one terminal coupled with one of the plurality of data lines, the conduction state of the first switching transistor being controlled by a scanning signal supplied via one of the plurality of scanning lines; and

a second switching transistor having one terminal coupled with one of the plurality of voltage supply lines and the other terminal coupled with the gate of the driving transistor.

3. The electro-optical device according to claim 1, the plurality of scanning lines including a plurality of first sub-scanning lines and a plurality of second sub-scanning lines,

each of the plurality of pixel circuits including a first switching transistor that has one terminal coupled with one of the plurality of data lines and whose conduction state is controlled by a first scanning signal supplied via one of the plurality of first sub-scanning lines, and a second switching transistor that has one terminal coupled with one of the plurality of voltage supply lines and the other terminal coupled with the gate of the n-channel driving transistor and whose the conduction state is controlled by a second scanning signal supplied via one of the plurality of second sub-scanning lines.

4. The electro-optical device according to claim 1, each of the plurality of voltage supply lines being settable to a plurality of voltages.

5. The electro-optical device according to claim 1, a current flowing through the driving transistor in an annealing period in a direction that is opposite to the direction in which the driving current flows.

6. The electro-optical device according to claim 1, the driving transistor in an annealing period being set to a conduction state equivalent to or lower than the lowest conduction state of the conduction states of the driving transistor set by the data current in the writing period.

7. The electro-optical device according to claim 1, the plurality of voltage supply lines being extended in the direction intersecting with the plurality of data lines.

8. An electro-optical device comprising:

a plurality of scanning lines;

a plurality of data lines;

a plurality of voltage supply lines extending in the direction intersecting with the plurality of data lines; and

a plurality of pixel circuits which are disposed at intersections of the plurality of scanning lines and the plurality of data lines and which are coupled in common to one of the voltage supply lines,

each of the plurality of pixel circuits including a driving transistor, an electro-optical element whose luminance is set in accordance with the conduction state of the driving transistor, and a capacitor having one electrode coupled with the gate of the driving transistor and the other electrode coupled with a node that couples the driving transistor and the electro-optical element, and

the capacitor retaining electric charge based on a data current supplied in a writing period before the driving period via one of the plurality of data lines.

9. The electro-optical device according to claim 8,

among the plurality of pixel circuits, a group of the plurality of pixel circuits being arranged in a direction in which one of the plurality of scanning lines is extended, and

the group being coupled with one of the plurality of voltage supply lines.

10. The electro-optical device according to claim 8,

each of the plurality of pixel circuits including the driving transistor, a first switching transistor being controlled by a scanning signal supplied via one of the plurality of scanning lines, and a second switching transistor that controls electrical coupling between the gate and the drain of the driving transistor,

all transistors included in each of the plurality of pixel circuits being only the driving transistor, the first switching transistor, and the second switching transistor.

11. An electro-optical device comprising:

a plurality of scanning lines;

a plurality of data lines; and

a plurality of pixel circuits disposed at intersections of the plurality of scanning lines and the plurality of data lines,

each of the plurality of pixel circuits including an electro-optical element, a driving transistor having a first terminal and a second terminal between which channel region is provided, a capacitor that has a first electrode coupled with a first gate of the driving transistor and a second electrode coupled with the first terminal, a first transistor that has a second gate coupled with one of the plurality of scanning lines and that has a third terminal and a fourth terminal between which a channel region is provided, and a second transistor that has a third gate and that has a fifth terminal and a sixth terminal between which a channel region is provided,

the fourth terminal being coupled with one of the plurality of data lines,

the electro-optical element being coupled with the first terminal, and

all transistors included in each of the plurality of pixel circuits being the driving transistor, the first transistor, and the second transistor.

12. The electro-optical device according to claim 11,

the fifth terminal being coupled with the first gate, and

the sixth terminal being coupled with the second terminal.

13. The electro-optical device according to claim 11,

the third terminal being coupled with the second electrode of the capacitor and with the first terminal.

14. The electro-optical device according to claim 11,

the fifth terminal being coupled with the first gate, and

the sixth terminal being directly connected to the third gate.

15. The electro-optical device according to claim 14, further comprising:

a plurality of first voltage supply lines; and

a plurality of second voltage supply lines,

the second terminal being coupled with one of the plurality of first voltage supply lines,

the sixth terminal being coupled with one of the plurality of second voltage supply lines, and

each of the plurality of second voltage supply lines being settable to a plurality of potentials.

16. The electro-optical device according to claim 14, further comprising:

a plurality of first voltage supply lines; and

a plurality of second voltage supply lines, the second terminal being coupled with one of the plurality of first voltage supply lines, the sixth terminal being coupled with one of the plurality of second voltage supply lines, and each of the plurality of second voltage supply lines being settable to either one of a predetermined voltage and a floating state.

17. The electro-optical device according to claim 15, the plurality of voltage supply lines being extended in the direction intersecting with the plurality of data lines.

18. The electro-optical device according to claim 14, further comprising:

a plurality of first voltage supply lines; and

a plurality of second voltage supply lines,

the second terminal being coupled with one of the plurality of first voltage supply lines,

the sixth terminal being coupled with one of the plurality of second voltage supply lines, and

one of the second voltage supply lines being set to a predetermined potential at least in part of a writing period in which the conduction state of the driving transistor is set according to a data current to pass through the second transistor.

19. The electro-optical device according to claim 11, the driving transistor, the first transistor, and the second transistor being formed of amorphous silicon.

20. An electronic apparatus comprising the electro-optical device set forth in claim 11.